During the manufacturing of semiconductor circuits, there is often a need to make temporary electrical connection to conduct testing operations. To allow this connection, the semiconductor circuit is fabricated with a plurality of miniature test contact pads at various locations on the surface of the silicon wafer. A probe card, having a plurality of needle-like probe pins, is then used to mechanically contact, and make electrical connection to, the test contact pads.
In using the probe pins to make connection to the semiconductor circuits, it is critical that the probe pins be aligned in two respects. First, the configuration of the probe pin tips must be such that it exactly matches the configuration of the test contact pads. Second, the respective probe pin tips must be on proper planar levels such that all the contact pins will make contact with the respective test contact pads at substantially the same time. It should be noted that tremendous skill and expertise must be used to make these critical alignments. Once aligned, the probe card represents a very delicate apparatus since the probe pins are very easily bent.
Another important feature of the probe card is the probe card circuitry which is comprised of a plurality of probe circuits, each of the respective probe circuits being associated with respective one of the probe pins. Although there is a tremendous number of probe circuit variations, the probe circuit associated with each probe pin is usually dependent on the type of semiconductor circuit to be tested and, also, on the type of test which is to be applied. As a result of the above dependencies, the probe circuits for the respective probe pins must be changed every time the semiconductor circuit type or testing operation is changed.
In the past, probe cards were fabicated as permanent structures; i.e., with probe circuits and probe pins which were an integral part of, or permanently attached to, the probe card. This approach is disadvantageous in a number of respects. First, there is a tremendous expense in fabricating, performing critical alignment, storing and indexing a large number of probe cards. Since these probe cards are not reconfigurable, a separate card has to be fabricated for every variation of probe card circuitry, even though a minor circuit change might have rendered an existing probe card suitable.
There is even a more important disadvantage. The excessive handling required by having to dismount and mount a large number of different probe cards results in a substantial increase in the probability that either improper testing will occur, or damage will be done to the very delicate semiconductor circuit or probe card. Furthermore, the dismounting and remounting of the probe pins from contact with the semiconductor circuit is an especially inefficient operation in cases where a series of different tests must be applied to the same semiconductor circuit.
One prior art appraoch, which has overcome several of these shortcomings, is that disclosed in PCT International Publication WO 80/00101, entitled "Probe and Interface Device for Integrated Circuit Wafers," dated 24th January, 1980 (Cerprobe Corp.). This prior art approach will be illustrated and described with reference to FIG. 1A-1C.
In FIG. 1A, there is shown a simplified top view of the prior art probe device 100 attached to coupling connector 102. Extending from the connector 102 are metalized portions 104 leading to a circular aperture 106. An enlarged view of this circular aperture 106 is shown in FIG. 1B.
Projecting toward the center of this circular aperture 106 is a plurality of probe members 110 which are attached to a plurality of respective holding means 112 which are removably maintained in respective holding grooves 114 and are electrically connected to respective metalized portions 104.
Turning now to FIG. 1C, there is shown an enlarged view of one of the holding means 112 which has an L-shape and has probing circuitry 116 which is electrically connected to the probe member 110. As the probing circuitry for a respective probe member 110 is formed on the removable holding means 112, it can be seen that the probe device 100 can be reconfigured to a different probe card circuitry.
This feature offers advantages over the permanent probe card approach in a number of respects. First, versatility is achieved in that the probe device 100 may be reconfigured or repaired by replacing any of the respective holding means 112. Thus, regardless of whether a slight or a major change is required, the probing device 100 can be reconfigured. As a further advantage, tremendous manufacturing savings are realized, as it is cheaper to manufacture the simpler L-shape holding means structures rather than an entire probe device.
Although the approach of FIGS. 1A-1C represents an improvement over the permanent probe card approach, it has been found still to be disadvantageous in several respects. First, in order for the probe card circuitry to be reconfigured, up to 24 individual L-shaped holding means 112 have to be removed from the holding grooves 114 and, then, replaced with new holding means. During replacement of the respective holding means 112, great skill and expertise must be used to align each of the new probing members 110 with respect to the other probing members. This operation is very time consuming, and there exists the danger that neighboring probing members 110 will be mechanically contacted and that the critical alignment will be disturbed.
As a further disadvantage, the probing device 110 must be dismounted from contact with the semiconductor circuit, reworked and remounted every time a change in the testing operation is to occur. Again, this is a particularly inefficient approach where a series of probing tests are to be applied to the same semiconductor circuit.
As a result of the deficiencies in the prior art, there has long existed the need for a probe card apparatus and method which allows convenient reconfiguration of the probe circuits. Furthermore, there has long existed a need for a probe card apparatus and method which facilitates reconfiguration without replacement of the probe pins, and without having to remove the probe pins from contact with the test contact pads.